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You don't NEED a DED but you do need a DSP that won't let the Jag amp be unhappy. Helix works very well. My previous AudioControl system did not.
What Audio Control unit did you have and what was the issue? I've got the D-6.1200 running from the front 6 channels from my 770W Meridian system. I'm just getting started so haven't hit significant problems yet. I'm also using AC load generators (AC-LGD 60).
Some tracks sounded good. Some just sounded weird. I believe AC was not able to make the JLR amp 100% happy and it was throwing square waves and distortion. AC is known to be noisy as well.
Some tracks sounded good. Some just sounded weird. I believe AC was not able to make the JLR amp 100% happy and it was throwing square waves and distortion. AC is known to be noisy as well.
Were you using load generators?
So I was trying to find the point where the system clips the other night and was getting a very jittery result and ultimately couldn't find a point where it was obviously clipping but I don't trust the result since it was so "dirty" to begin with. This is a very cheap o-scope but I tested it on my other car last night and it didn't look like this so I'm assuming it's something with the Meridian system. This was a 1khz tone from the midrange.
You saying you limit the volume control to 25 max? That's interesting because I also found out that the Meridian system stops increasing the sub frequency output at 28. I was scoping with a 50Hz tone and just my sub playing. I could hear the volume increase with every click up until 28 and then it held rock steady at that level all the way to max (60). I'm going to repeat with a series of tones working up from 50Hz to see if it's a sharp cutoff or maybe they gradually roll it off. all I know right now is that at 50Hz it's a hard cutoff at 28 on the volume knob.
I’m not using the sub channels as input. It’s not musical. There is plenty of bass in the door’s.
I'm not talking about the rear sub channels. The door midbass outputs have the sub frequencies also. The Meridian system still caps the output (at 50Hz at least) beyond 28 on the volume so it's good that you aren't going past that with your tune.
Using the Helix DSP PC-Tool by Audiotec Fischer allows you to analyze the analog high-level inputs from the Meridian amp. You can then attempt to sum and flatten them for input into the DSP, not a fun job IMHO.
If you have a digital preamp with digital out (DED or MOST) you don't need to do this, and you have no issues with setting gains and clipping.
25 sounds about right for when clipping appears, it's not a clean signal and has the roll-off as you mention.
My information from the factory AC tech was just because you can sum inputs doesn’t mean you should. Often times leads to unforeseen complications and in the case of The Jag, the three channels on each door have all the data you need and are crossed over giving plenty of wiggle room.
When the door has a full range signal, absolutely! You could just use those two inputs for the DSP, but there needs to be loads on the other outputs for the Meridian amp.
Other thing I ran into: Checking the polarity of the speakers after the install is key - the DSP often changes the polarity during tuning and time alignment so you can't go based on the + and - of the wires.
My information from the factory AC tech was just because you can sum inputs doesn’t mean you should. Often times leads to unforeseen complications and in the case of The Jag, the three channels on each door have all the data you need and are crossed over giving plenty of wiggle room.
I'm not understanding what you're saying here. Yes, the three door channels collectively contain the full frequency spectrum (aside from what the factory DSP attenuates on the woofer channel), but they still need to be summed in order to customize the frequency bands and slopes for new speakers and tuning.
@TH3FRB you are correct - one must sum the 3 door signals unless one wire has a full range signal. I haven't checked this. @Robtrt8 - have you?
Summing is a great way to get a full range signal and you can adjust the % input etc. I see no downsides except that polarity should be checked at the end of the tune.
@Robtrt8 can you elaborate about the "unforeseen complications" you mention? We are here to learn from your wisdom and knowledge as a Vanguard on the topic.
Now to flatten the Meridian output signals is another matter. Here is a great video using the DSP PC-Tool:
The problems with using the high-level analog outputs from the Meridian amp are:
1) All outputs must be connected to a load regardless if they are being used or not by the DSP, or else the Meridian amp may shut down in protection mode.
2) The door outputs are 3 separate wires for the tweeter, mid-range and woofer. I doubt one wire has a full range signal but I could be wrong. Then you will need summing.
3) The bass roll-off from the Meridian dual sub outputs is real and should be avoided altogether unless you sum. This was done to lower sub rattling from the rear compartment as the volume was turned up and visits to the dealer from unhappy customers!
4) You must center and have neutral equalization from the Jag head unit for DSP tuning and time alignment.
5) For those with Meridian Surround you must take the center speaker into consideration.
@TH3FRB you are correct - one must sum the 3 door signals unless one wire has a full range signal. I haven't checked this. @Robtrt8 - have you?.
Each of the 3-way speakers in the door is most definitely running a specific band. I'm currently just passing them through my Audio Control D-6.1200 but I've played with listening to isolated pairs when I was getting set up. The unknown is exactly what the x-over points and slopes are. Since I'm currently using the stock "upgraded" speakers I haven't summed everything and split it back out again.
Another note - I eliminated the rear "subs" completely and have no load on those two channels. It's been like that for over a year with no apparent issues.
When I had the DM-810 and LGD's, my Jag amp was definitely not happy. I had LGD's on every signal path thinking it was necessary.
My Jag amp is connected to the HU via DED, not MOST. Had it been MOST I definitely would have used a MOST decoder.
Finally gave up and changed to Helix.
I do not have "loads" on any of the rear or center channels and the Jag amp is not exhibiting any of the weirdness. Whatever Helix has done to make the factory system happy, it works.
On a previous recommendation from the AC rep, (he actually recommended installing the AC BT accessory) I installed the Helix BT HEC card to see what a direct signal (no Jag baloney) would sound like. I found it very flat and lifeless, so I gave up on that.
I found the existing high level door signals covered all the frequencies that I needed so there was no need to combine the signals. I did raise the gain on the mid signal a bunch and dropped the mid bass signal a bit for the doors. I'm using the door's mid bass signal for the 8's and the 12 in back. I dropped the 8's quite a bit and bumped up the sub a bit.
I applied my own measurements for time alignment including "placing" the 8's and 12 a whole bunch forward.
Then I finally got my Helix trained buddy to run the Helix auto tune program. It did some crazy EQ stuff but basically accepted my TA and gain values.
On a side note, I installed my old DM-810 in my Jag mechanic's old BMW 3 with some Helix Compose drivers and his crap Chinese Android HU and it sounds great.
I do find the AC tuning program much easier than the Helix software.
I installed an LC 4-800 in a buddies wake boat for the tower Kicker 11's and it works great.
So I'm definitely not knocking AC. Just didn't work integrating a factory JLR system.
When I had the DM-810 and LGD's, my Jag amp was definitely not happy.
I found the existing high level door signals covered all the frequencies that I needed so there was no need to combine the signals.
Thanks for the additional info. What did you experience that makes you say the jag amp was "not happy" - what symptoms? I'm trying to understand what I should be looking out for since I'm currently going down the road of high level inputs to my AC DSP/amp.
So you are just running whatever x-over points and slopes Jag uses for the stock components to run your AF and Morel speakers? That's probably not ideal for those drivers but maybe you got lucky and it's close enough. I'm sure the time alignment and level matching helps a lot regardless. I assume you haven't done any tuning with a microphone and REW to analyze the speaker output frequency response? That's typically where tweaking x-over points helps address problems in the frequency response.
